FIG. 1 illustrates a wheelchair input device 10 that includes a proportional joystick 12 and a signal converter 22. The joystick 12 includes a housing 15 in which a gimbal 14 is movably mounted. Due to the internal configuration of the joystick, the gimbal is free to move within the housing along a hemispheric surface, such that each position of the gimbal corresponds to a unique two dimensional position. The two dimensional position coordinates for the gimbal are communicated by two potentiometers as will be described in more detail below. In addition to moving along the hemispheric surface, the gimbal can also be moved in a direction perpendicular to the hemispheric surface as indicated by the phantom lines in FIG. 1. This perpendicular actuation closes a switch located in the bottom of the housing. The switch provides a binary output for wheelchair control. Outputs 16 of the joystick's potentiometers and the switch are connected to the signal converter 20 that converts the signals into wheelchair control signals that can be received by a wheelchair controller and used to set various wheelchair operating parameters. A connector 22 plugs into a standard port of the wheelchair controller. While a hemispheric joystick actuation surface is described herein, other surfaces such as a plane or other appropriate surface may be employed to implement the input device.